The invention relates to a method for separating abdominal fat from abdominal skin of a slaughtered bird, comprising: positioning a supporting surface against at least a part of the side of the abdominal skin which is remote from the abdominal fat, and scraping at least a part of the abdominal fat off the abdominal skin with the aid of a movable scraper member. The invention also relates to a device for carrying out the method.
A bird has abdominal fat in the abdominal cavity against the abdominal skin in the region between the cloaca and the sternum. When the bird is slaughtered, without special measures the abdominal fat remains attached to freely hanging parts of the abdominal skin of the carcass after the viscera have been removed therefrom via an abdominal opening.
Nowadays, traders in slaughtered poultry products impose different demands on the removal of abdominal fat from abdominal skin of poultry depending on specific consumer requests. In some cases, it is required for all the abdominal fat to be removed from the carcass (and for the abdominal skin to remain on the carcass), but in other cases there is also a demand for the possibility of selective removal of abdominal fat, meaning that the amount of abdominal fat to be removed must be adjustable from 0% to 100% (with the abdominal skin remaining on the carcass). In addition, there is a demand for an increase in the quality of the abdominal fat obtained by avoiding the abdominal fat of a bird being recovered in many pieces and/or by avoiding contamination to the abdominal fat obtained by moisture and other tissue, such as pieces of intestine or kidneys. If it forms a substantially cohesive unit and is free from contamination, the abdominal fat can be processed further as a high-grade product and can be redistributed to slaughtered poultry products, for example as natural product fat. Furthermore, there is a demand for it to be possible to remove the abdominal fat either before cooling of the carcass or after this cooling, as desired. In this context, the fact that the mechanical properties of the carcass, and in particular of the abdominal skin and of the abdominal fat, differ considerably before and after cooling has to be taken into account.
The separation of abdominal fat from abdominal skin is known from the prior art.
European Patent Application 486,099 discloses a device and method in which an oval, conical head with a scraping edge is passed through an abdominal opening into the body cavity of a slaughtered bird which is hanging by its legs from a hook. Behind the head there is an elongate, axially movable, hollow mandrel with transverse dimensions which are smaller than those of the head. Furthermore, behind the head there is an annular supporting member which can move in the same direction as the mandrel and the transverse dimensions of which substantially correspond to those of the head. The supporting member can be pressed onto the rear side of the head by means of spring means. As a result of a subatmospheric pressure being created in the mandrel, abdominal skin is sucked along the head into the mandrel. Then, the supporting member is moved towards the head, so that the abdominal skin is clamped between the head and the supporting member. Then, the head is moved out of and, together with the supporting member, away from the carcass, the abdominal fat being scraped off the abdominal skin at the location of the scraping edge of the head. The abdominal fat which is scraped off is sucked away via the mandrel.
One drawback of the known device is that the head is bulky, and consequently there is a risk of abdominal skin being torn into and torn off as a result of displacement. Therefore, detached pieces of abdominal skin may pass into the abdominal fat removed, which is highly undesirable since such pieces impair the quality of the abdominal fat or subsequently have to be removed again from the abdominal fat obtained in order to achieve a high quality. Secondly, the presence of abdominal skin in abdominal fat reduces the weight of (the carcass of) the bird, so that the yield from the bird is lower.
The use of vacuum to suck away abdominal fat has the drawback that the abdominal fat is removed in pieces and that all kinds of undesirable substances and pieces of tissue (such as pieces of intestines and kidneys) which are situated in the airstream sucked away may find their way into the abdominal fat removed, with the consequences discussed above.
In the known device, there is also a risk of abdominal skin being torn into and torn off on account of the fact that the movement of the scraper member, i.e. the scraping edge of the head, is directed substantially perpendicularly to the supporting surface which interacts therewith, i.e. the bottom side of the annular supporting member. As a result, the scraping edge may tear the abdominal skin in the event of a heavy load being imposed on the abdominal skin as a result of the scraping. In the embodiment selected, the load on the abdominal skin is high on account of the fact that both the scraper member and the supporting surface are moving in the same direction relative to the abdominal skin.
Another drawback of the bulky nature of the known device is that consequently the freedom of design decreases with respect to the design of the bird-conveyor hook, which must not interfere with one another.
Yet another drawback of this known device is that it is unsuitable for use on carcasses which have been cooled, since the abdominal skin, which is relatively rigid on account of the cooling, cannot be sucked into the mandrel.
It is an object of the invention to provide a method and device which provide a low load on the abdominal skin and high efficiency of removal of abdominal fat and which can be used on both uncooled and cooled carcasses.
Another object of the invention is to provide a device which is of simple design and not very bulky.
A further object of the invention is to provide a device which allows selective, i.e. optionally complete or partial, removal of abdominal fat.
Yet another object of the invention is to provide a method and device with which abdominal fat can be obtained as a high-grade product, i.e. substantially as a whole and/or substantially without contamination.
To achieve one or more of the abovementioned and other objects, the method according to the invention is wherein the movement of the scraper member is directed substantially parallel to the supporting surface. First displacement means are provided for implementing this feature in the device according to the invention. By virtue of this feature, the load on the abdominal skin is relatively low, thus preventing undesirable tearing of the abdominal skin both in the case in which the supporting surface adopts a substantially fixed position with respect to the abdominal skin during the scraping operation and in the case in which the supporting surface moves with respect to the abdominal skin, in the same direction as the scraper member or in the opposite direction, during the scraping operation.
Preferably, the supporting surface is moved to the vicinity of the edge of an evisceration opening of the bird immediately prior to the scraping operation, and in particular the supporting surface is positioned on the side of the sternum of the bird. The abdominal skin can then be brought into contact with the supporting surface over its maximum surface area, so that the removal of abdominal fat can be carried out optimally. To achieve a selective harvesting of abdominal fat, it is obviously also possible for the supporting surface to be moved at least partially into the abdominal cavity of the bird immediately prior to the scraping operation, if only a part of the abdominal fat is to be obtained. In this case, the supporting surface will shield part of the abdominal skin, making it inaccessible to the scraper member. Another possibility for harvesting only a part of the abdominal fat which is present is for the supporting surface to be moved no further than to a distance from the edge of and outside the abdominal cavity of the bird. In this way, it will not be possible for the scraper member to scrape off the abdominal fat which is situated on a part of the abdominal skin which extends between the abdominal cavity and the supporting surface. Yet another possibility for obtaining part of the abdominal fat which is present is for the scraper member not to be allowed to execute a complete movement along the supporting surface. Yet another possibility for obtaining part of the abdominal fat which is present is to select a predetermined distance at which the scraper member moves along the supporting surface.
It will be clear that the possibilities discussed above for obtaining a selectivity in terms of the extent of abdominal fat recovery may be used both separately and in various combinations with one another, both for each processed bird and for each series of processed birds, by means of suitable data-based control of the device according to the invention. Moreover, the selective removal of abdominal fat can be carried out not only in the method and device according to the invention but also in other methods and devices for removing abdominal fat, such as those according to the prior art.
To allow the abdominal skin to be taken optimally against the supporting surface, the scraper member is preferably moved at least partially into the abdominal cavity of the bird prior to the scraping operation.
Expediently, an active section of the scraper member, while it is being introduced into the abdominal cavity of the bird, is situated, as seen in a direction perpendicular to the supporting surface, at a first distance from the supporting surface, and during at least part of the scraping operation is situated at a second distance from the supporting surface, the second distance being shorter than the first distance. Therefore, prior to the scraping operation, the active section moves towards the supporting surface, which movement can take place from various starting positions and along various paths.
In a preferred embodiment of the method according to the invention, the abdominal side of the bird faces upwards during the scraping operation.
In a further preferred embodiment of the method according to the invention, the abdominal fat is taken, mechanically and under atmospheric conditions, between the supporting surface and the scraper member prior to the scraping operation. Consequently, the use of vacuum with the associated risks is avoided. Incidentally, the use of this measure is not limited to the method and device according to the invention.
In a preferred embodiment of the method according to the invention, the abdominal fat situated between the supporting surface and the scraper member is gripped securely by a gripper member during the scraping movement, or at least a part thereof. Gripping the abdominal fat during the scraping movement allows the abdominal fat to be removed in a very controllable way and a gentle pulling action also emanates from the scraping movement, thus promoting the ultimate scraping action. The gripper member may, for example, be pivotably connected to the scraper member.
In another preferred embodiment of the method according to the invention, the abdominal fat is completely or partially cut free from the abdominal skin during the scraping movement or at least a part thereof.
In a preferred embodiment of the device according to the invention, the supporting surface comprises one or more substantially flat faces. In this way, it is possible to obtain a simple form of the device, in particular if the supporting surface is formed by one or more plates which optionally adjoin one another and are connected to one another.
The scraper member preferably comprises a bracket, in particularxe2x80x94with a view to mechanical strength and limited use of materialxe2x80x94a continuous bracket which delimits an opening. If the bracket is formed in such a manner that its transverse dimension decreases towards the front end (i.e. the end which is intended to be the first to reach a bird when carrying out an operation of removing abdominal fat) of the bracket, the forces acting on the bracket are distributed during the operation of removing abdominal fat. This measure also allows easy entry for the scraper member.
In an alternative embodiment, the bracket comprises at least two bracket parts which are displaceable with respect to one another and are preferably pivotable with respect to one another. This measure allows the size of the scraper member to be reduced considerably in particular while it is being introduced into the bird, thus reducing the risk of undesirable damage to the bird and/or the skin.
In an alternative embodiment of the device according to the invention, the scraper member comprises a gripper member which is pivotably connected thereto and with which part of the abdominal fat which is to be removed is gripped during the scraping operation, leading to an improved scraping action.
These and other aspects, features and advantages of the present invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings, in which identical reference numerals denote identical or similar components.